This invention relates to a filter assembly for filtering air. Filter assemblies are widely used for filtering air which is either exhausted from an enclosure or supplied to an enclosure. For example, an enclosed room might be provided with an air intake through which air is supplied, or a work area might be provided with an air exhaust through which air is removed. The invention can be used in any environment in which it is desired to filter air, either intake air or exhaust air. However, for purposes of describing a specific embodiment of the invention, the invention will be explained in conjunction with a fume hood.
Fume hoods conventionally include an enclosed chamber which provides a work area where laboratory work with chemicals which give off noxious or malodorous fumes can be carried out. An exhaust duct is connected to the work enclosure, and a blower fan within the exhaust duct withdraws the fumes from the fume hood and expels air into an area remote from the laboratory, for example, outside of the laboratory building.
In order to ensure that the exhaust system does not expel pollutants into the atmosphere, the exhaust system should be equipped with a filter. However, filters which are effective in trapping certain pollutants are often quite cumbersome, and the filters require frequent replacement in order to maintain their effectiveness. The filters are generally interposed in the ductwork so that all of the air exhausted through the ductwork passes through the filter. Accordingly, replacement of the filter generally requires at least partial dismantling of the exhaust system ductwork.
The invention provides a filter assembly which is connected to the ductwork but which permits the filter to be readily removed and replaced while the ductwork remains securely in place. The connecting members which extend between the first and second portions of the filter housing clamp the two housing portions against the filter to maintain an effective seal when the filter is in place. When the filter is to be removed, the second housing portion is moved along the connecting members, and the second housing portion and the ductwork extending from the second housing portion are securely supported by the connecting members.